Question

3. Average height of 15 students of class 6 is 140 cm and average height of 10 students of class 7 is 145 cm
What is the average height of the students of both the classes?​

Answer 1

In the above Question, the following information is given -

The average height of 15 students of class 6 is 140 cm and the average height of 10 students of class 7 is 145 cm.

To find -

What is the average height of the students of both the classes?

Solution :

Here, The average height of 15 students of class 6 is 140 cm.

From this, we can get that -

Sum of the heights of all the Class 6 students -

=> [ Sum of heights of all class six students ] / 15 = 140 cm

=> Sum of heights of all class six students = 140 × 15 cm

=> Sum of heights of all class six students = 2100 cm .

Similarly, we can do the same for the class 7 students -

Here, The average height of 10 students of class 7 is 145 cm.

From this, we can get that -

Sum of the heights of all the Class 7 students -

=> [ Sum of heights of all class 7 students ] / 10 = 145 cm

=> Sum of heights of all class 7 students = 145 × 10 cm

=> Sum of heights of all class 7 students = 1450 cm .

Now, adding the two,

Some of the heights of all the class 6 and class 7 students -

=> 2100 cm + 1450 cm

=> 2550 cm .

The total number of students in class 6 and 7 cumulatively is -

=> 25

The required average height of the students of both the classes -

=> [ 2550 / 25 ] cm

=> 102 cm .

This is the answer.

________________________________________________________________________

Answer 2

◘ Given ◘

$\bigstar$ Average height of 15 students of class 6 is 140 cm.

$\bigstar$ Average height of 10 students of class 7 is 145 cm.

◘ To Find ◘

The average height of the students of both the classes.

◘ Solution ◘

For class 6,

(Sum of heights of all the students) / (Number of students) = Average

Let the sum of heights of all the students be x.

➞ x/15 = 140

➞ x = 140 × 15

➞ x = 2100

___________________

For class 7,

(Sum of heights of all the students) / (Number of students) = Average

Let the sum of heights of all the students be y.

➞ y/10 = 145

➞  y = 145 × 10

➞  y = 1450

___________________

Average height of students of both the classes, A = (x + y) / (15 + 10)

➞ A = (2100 + 1450) / 25

➞ A = 3550 / 25

➞ A = 142 cm

Therefore, the average height of students of both the classes is 142 cm.